Farm Animal Digestion and Nutrition

fermentation is microbial digestion without ? (endproducts = VFA)

oxygen

microbial digestion of fiber is ?, so longer retention time of fibrous food is necessary

time consuming

the forestomach is ? and of little use in the first 2-3 weeks of life, so milk bypasses to the abomasum

immature

the reticulo-omasal orifice lies below the ? level in the reticulorumen

fluid

Hydrostatic pressure is required to force the rumen contents into the abomasum is always present, but transfer can only take place during the second reticular contraction, when the sphincter surrounding the omasal canal is ?

relaxed

the size, shape, density, and digestibility of the ? in the reticulorumen determine how long they are retained before passing to the omasum

particles

What are the layers of contents in the rumen from top to botton

• gas (CO2, CH4, H, N)

• actively fermenting plant material

  • soupy, finely dispersed plant material

Unlike grazers, the rumen contents of ? is pulpy, relatively homogenous, and ferments quickly througout the content

browsers

what are the functions of the reticulum and rumen contractions

1. mixing forestomach contents and transporting them to the omasum

2. moving contents to oral cavity (regurgitation) for rumination

   1. aid in gas removal (eructation)

what are the three types of contractions in the rumen and reticulum

• mixing (primary contractions)

• contractions leading to rumination

  • contractions leading to eructation of gas (secondary)

How many mixing contractions in the reticulum occur per minute

2 reticular contractions per minute

what contracts first in a contraction cycle

reticulum

when is rumination most active

night and afternoon rest

contractions of the rumen that allow for gas eructation are called ? contractions, usually 2-3 primary contractions betwene each

secondary

accumulation of gas in the forestomach due to failure to eructate gas is called ?

bloat

What are clinical signs of bloat

• distended left paralumbar fossa

• discomfort (grunting, colic)

• open mouth breathing

• anorexia

• salivation

• anxious behavior

• depressed terminally

• sudden death eventually

what are the types of bloat

primary (frothy)

secondary (free gas)

what is the pathology behind primary bloat

eructation normal, cant expel (legumes, grains)

What is the pathology behind secondary bloat

failure of eructation (esophageal FB, vagus indigestion, positional, hypocalcemia, pharyngitis)

what are treatments for secondary bloat

• pass a stomach tube either nasogastric or orogastric

• if positional, roll cow into sternal recumbency

• force exercise

• if hypocalcemia, administer calcium

• rumen stimulents

  • rumen trocharization for emergencies only

what are treatments of frothy bloat

reduce surface tension by consolication of bubbles

• poloxalene- 1 or 2 ox

• household detergent (tide, 2-3oz)

• mineral oil

  • dioctyl sodium sulfosuccinate (DSS)

what are the sensory cells in the wall of the rumen and reticulum with afferent vagal fibers that regulate forestomach contractions?

• stretch sensitive sensory cells in the smooth muscle of rumen with tension receptors - react to stretch

  • sensory cells with both mechano- and chemoreceptors have epithelial receptors in basal layer of rumen- react to stretch, pH, osmolarity, and concentrations of VFAs

moderate distension of forestomach stimulates stretch receptors and ? motility and rumination, but if the rumen and reticulum are over distended as in bloat, epithelial receptors are stimulated and motility s ??

increases, inhibited

? distension slows reticulorumen contractions

abomasal

rumen pH of < ? inhibits rumen contractions

5

? nuclei are responsible for central regulation of motility - regulate rate and force

dorsal vagal

both efferent and afferent nerve fibers in the reflex arc are contained in the vagal nerves- called the ? reflexes

vago-vagal

what signals do the regulating center of the forestomach contraction recieve to influence force and frequency

1. sensory cells in forestomach

2. impulses from the olfactory organ, taste buds, and stretch sensitive sensory cells in the oral cavity

3. external factors affecting the ANS such as stress or pain

after feeding, osmolarity of the rumen ? = could also be due to a diet high in starch (rapidly degraded to VFAs)

increases

increased osmolarity causes fluid to move into rumen by ?

osmosis

increased ? production also contributes to increased rumen fluid volume

saliva

what are the three main classes of microbes in the rumen

bacteria, protozoa, fungi

most bacteria in the rumen are ?

anaerobic

how do bacteria maintain the anaerobic conditions in the rectiulorumen to prevent degradations of nutrients all the way to CO2 and water

attach to the rumen wall and utilize O2 that diffuse through epithelium from the blood

Where is the majority of the VFAs, lactic acid, water, electrolytes absorbed?

rumen

rapid ? in feed, composition or amount, can result in large alterations in the number of different microorganisms

alterations

to become established, each type of microorganism must have a ? time in the reticulorumen that exceeds its lifespan

retention

how is the rumen microflora established?

• neonate digestive tract is sterile at birth, but sucking teats and skin of mother results in transfer

• mother liking neonate

what are the three VFAs produced in the rumen by the bacteria breaking down carbs?

acetic, butyric, propionic acid

What other substances are produced by the rumen bacteria

lactate, succinate, ethanol, hydrogen gas, methane,, CO2

? rumen bacteria break down nutrients in the feed

primary

? rumen bacteria utilize products formed by the primary bacteria

secondary

what is the function of amylolytic bacteria

metabolize starch and other soluble carbohydrates (excluding celluose or other plant structural carbs)

What is the function of cellulolytic vacteria

degrade cellulose, hemicellulose, fructosans, and pectin

WHat is the function of proteolytic bacteria

breakdown peptides to amino acids

What is the function of methanogenic bacteria

responsible for reducing CO2, aking methane gas (30-40% of rumen gas)

you prefer gram ? bacteria in the rumen because the other produces lactic acid and can lead to acidosis

negative

what are the types of protozoa found in the rumen

• ciliates - anaerobes that produce VFA, lactate, CO2 and hydrogen from all types of plant material

  • flagellates

how do the anaerobic fungi function in the rumen

attach to plant fibers containing lignin and project hyphae which penetrate the fibers and split them

what changes occur in the reticulorumen after feeding

• fermentation and gas production increase rapidly after feeding

• concentrations of VFAs and NH4+ increase in reticulorumen

• pH decreased with increased VFAs

? represent the main source of dietary energy in the ruminant

VFAs

how does breakdown of carbs form fatty acids in the rumen

• bacterial breakdown of cellulose (hydrolysis) results in crelease of glucose

• glycolysis results in 2 molecutes of pyruvate from each molecule of glucose

• from this anaerobic metabolism comes VFA production

the majority VFA in the rumen is always ?

acetate

what diet scenario can cause a higher ratio of acetate

higher fiber diets such as dairy cows on pasture

what diet scenario causes a lower ratio of acetate

high concentrate diet such as feedlot steers

What the diet is high in starch, the total VFA production is ? than high fiber diets

higher

? acid production is higher when diets high in starch are fed

propionic

Which VFA is the only one that came be converted into glucose in animal cells?

propionic acid g

what can be the results of ruminant carbohydrate engorgement

grain overload
lactic acidosis
carbihydrate intoxification
grain engorgement

What history is expected with acidosis

• access to highly fermentable feedstuffs to unaccustomed animals or in larger amounts

• may involve several animals in herd

  • rapid clinical course

how does acidosis occur?

• excess carbohydrate ingestion, including VFA, lowers the rumen pH and motility.

• strep bovis proliferates, producing lactic acid which lowers the rumen pH

• the acid resistant Lactobacillus spp proliferate and produce even more lactic acid

how does acidosis affect osmolarity of the rumen

more body water is taken into the rumen, creating a “splashy rumen”. This causes dehydration that contributes to the condition

how does the excess lactic acid in acidosis affect the rest of the body

lactic acid is absorbed from the rumen and small intestines, causing profound lactic acidosis

how does the change in rumen pH in acidosis affect the animal?

lower pH damages mucosal surfaces in the stomach and intestins, causing blood vessels to thrombose and sections of rumen mucosa and submucosa to slough and allowing bacterial invasion

how does “wandering rumen bacteria” affect the body in acidosis

travel to liver via portal circulation and cause liver abcesses

mycotic rumenitis may develop

how does acidosis affect the production pf certain hormones and other products, and how does this affect the body?

• histamine levels increase

• ethanol, methanol, tyramine, tryptamine production contribute to CNS

• thiaminase production may result in the development of polio

What is the consequence of the death of gram negative bacteria in acidosis

endotoxin release

what are the clinical signs of acidosis

• abdominal pain

• dehydration 6-12%

• fluid and fetid diarrhea

• splashy rumen, bloat

• depression

• lameness

• elevated temp initially, may be subnormal when present

• HR = 80-140bpm

• RR elevated to blow off CO2

What clinical signs of acidosis are found on lab work?

• rumen fluid analysis will present a pH of <5, sour odor, protozoa dead, predominance of gram + bacteria

• metabolic acidosis

• increased PCV

• increase dprotein

• elevated BUN, creatinine, phosphorous

• increased anion gap

• decreased calcium

what feeds can cause carbohydrate engorgement

• cereal grains

• industrial by-products (brewers’ grains, sugars)

• fruits

• tubers

  • finely ground feeds with large surface area to promite fermentation

why are hay and grass not highly fermentable

cellulose and large particulate size

why is corn silage usually not an issue with carbohydrate engorgment

much of CHO already reduced to VFA in ensiling process, large particle size

what are treatments for acidosis

• remive rumen contents via kingman tube, rumenotomy, ice water administration, procaine pen G (10 million IU PO)

• fluid and electrolyte replacement IV

• anti inflammatory agents such as Flunixin meglumine (Banamine)

• antibiotics

• antimycotic therapy

• rumen transfaunation

• Thiamine

  • B complex vitamins

what are ways to prevent acidosis

make diet changes very gradually! rumen takes 6 weeks to adjust

do not give small ruminants free access to most food sources

fat is metabolized like ? in ruminants, and must pass through abomasum and rest of GIT

monogastrics

some of the AAs from protein are utilized by bacteria and others are deaminated, forming ?

ammonia

what are the sources of the AAs absorbed by the small intestines

• feed proteins which pass undigested through the forestomach (bypass protein)

  • microbial proteins synthesized in the rumen

due to continual transport of forestomach contents to the abomasum and small intestines, certain proteins escape bacterial degradation known as ?

bypass proteins

the supply of protein often limits ? production, so the feed industry has developed methods to reduce protein degradation in the reticulorumen to increase nutritional value of feed

milk

? passes unchanged across the rumen wall

acetate

some proprinate is metabolized to ? during its movement through the epithelium, the remainder is converted to glucose in the liver

lactate

almost all of the absorbed butyrate is converted to ? during movement through the rumen wall

B-hydroxybutyrate

what makes a ruminant GI unique

• complex stomach

• microbial population in rumen

• microbial crude protein

• foregut fermentation

• VFA in rumen 70-80% of energy

• need fiber in diet (forage:concentrate ratio)

• effect of diet on mcrobial population

• importance of rumen pH 5.8-6.4

how many carbons to the main VFAs

acetate -2

propionate -3

buytrate -4

what VFAs especially stimulate papillae development in calves

propionic and butyric acids

a calf’s population of rumen microorganisms must be established before ?

weaning

Intake of highly digestible ? stimulates rumen development in calves

starter

what are the advantages of ruminants?

• utilize fibrous feeds

• microbes can turn poor quality proteins into high quality microbial proteins

  • microbes synthesize water soluble vitamins and vitamin K

what are disadvantages of ruminants?

• fermentation of high energy feeds yields less digestible energy to the animal than digestion in the small intestines (heat of fermentation, gas production, end products)

• conversion of high quality dietary protein to microbial protein may result in decrease in biological value

rumen pH less than ? will lead to acidosis

5.5

what are important feeding considerations for maintaining rumen health

• roughage concentrate ratio

• frequency of feeding

• feed particle size

  • whether total mixed ration or fed separately

what tests can evaluate forage quality and are very important

CP

NDF

ADF

what measures most of the structural components in plant cells such as lignin, hemicellulose, and cellulose, but not pectin?

neutral detergent fiber (NDF)

what measures the fraction of undigestible plant material in forage, usually cellulose fiber coated with lignin?

acid detergent fiber (ADF)

what are the two sites of energy in forages at a cellular level?

• cell contents such as sugars, starches, and proteins

  • cell walls such as cellulose, lignin, hemicellulose

what VFA is important in milk fat production

acetic acid

What are the primary dietary CHO sources

starch and cellulose

Structural (NDF) and nonstructural carbohydrates (NSC sugars and starches) produce ?

VFAs

What VFA is the highest in high grain diets, is conerted to glucose on the liver, and is used in lactose synthesis?

proprionic acid

what VFA is converted to ketones and is used for fatty acid synthesis in adipose and mammary glands?

Butyric acid